Antimicrobial susceptibility and pathogenicity of Escherichia coli strains of environmental origin / Suscetibilidade antimicrobiana e patogenicidade de amostras de Escherichia coli de origem ambiental

The study aimed to evaluate the antimicrobial susceptibility of 109 samples of Escherichia coli (E. coli) of environmental origin and to characterize these isolates according to the degree of pathogenicity in vivo, verifying a possible relationship between this variable and susceptibility to the active principles tested. The isolates were subjected to disc diffusion test to 14 antibiotics. From 16.5% to 90% of the samples were sensitive; 1 - 28.5% showed intermediate degree of susceptibility and between 9 to 78% of E. coli analyzed were resistant. The highest resistance percentages were seen in the class of quinolones and tetracyclines (>75%), and for sensitivity in the class of amphenicols (68.8%). By inoculating 1- day - old chicks, the isolates were classified as highly pathogenic (2.7%), intermediate (10.1%), low (42.2%) and apathogenic (45%). It was observed a wide variation in the susceptibility profile of isolates in relation to antimicrobials. It was also found that most of the samples had pathogenic potential (55%), thus being considered as APEC (avian pathogenic E. coli). No relationship between pathogenicity and antimicrobial susceptibility (P≤0.05) was observed.

O estudo teve como objetivo avaliar a suscetibilidade antimicrobiana de 109 amostras de Escherichia coli (E. coli) de origem ambiental frente a antibióticos e caracterizar esses isolados quanto ao grau de patogenicidade in vivo, verificando-se uma possível relação entre esta variável e a suscetibilidade aos princípios ativos testados. Os isolados foram submetidos ao teste de disco-difusão para 14 antibióticos. Entre 16.5% a 90% das amostras foram sensíveis, 1-28.5% apresentaram grau de suscetibilidade intermediário e entre 9-78% das E. coli analisadas foram resistentes. Os maiores percentuais de resistência foram encontrados para a classe das quinolonas e das tetraciclinas (>75%), e de sensibilidade para a classe dos anfenicóis (68.8%). Por meio da inoculação em pintinhos de um dia de idade, os isolados foram classificados como sendo de patogenicidade alta (2.7%), intermediária (10.1%), baixa (42.2%) e apatogênicos (45%). Foi observada uma ampla variação no perfil de suscetibilidade das amostras frente aos antimicrobianos. Verificou-se também que a maioria apresentou potencial patogênico (55%), sendo, portanto, consideradas APEC (E. coli patogênica para aves). Não foi observada relação entre a patogenicidade e a suscetibilidade aos antimicrobianos (P≤0.05).

Genomic characterization of novel circular ssDNA viruses from insectivorous bats in Southern Brazil.

Circoviruses are highly prevalent porcine and avian pathogens. In recent years, novel circular ssDNA genomes have recently been detected in a variety of fecal and environmental samples using deep sequencing approaches. In this study the identification of genomes of novel circoviruses and cycloviruses in feces of insectivorous bats is reported. Pan-reactive primers were used targeting the conserved rep region of circoviruses and cycloviruses to screen DNA bat fecal samples. Using this approach, partial rep sequences were detected which formed five phylogenetic groups distributed among the Circovirus and the recently proposed Cyclovirus genera of the Circoviridae. Further analysis using inverse PCR and Sanger sequencing led to the characterization of four new putative members of the family Circoviridae with genome size ranging from 1,608 to 1,790 nt, two inversely arranged ORFs, and canonical nonamer sequences atop a stem loop.

The constitutive expression of the V gene of Parainfluenza virus 5 affects the growth properties of bovine herpesvirus 5

This study aimed to analyze the effect of the expression of Parainfluenza virus 5 (PIV5) V protein in bovine cells on the replication of Bovine herpesvirus 5 (BoHV-5). Growth properties of BoHV-5 were evaluated in parental and PIV5 transfected cells. In one-step growth experiments, the BoHV-5 reached higher titers at earlier time points in the transfected cells when compared to the parental cells. The mean plaque size produced by the BoHV-5 in transfected cells was larger than the parental cells. This indicated that the expression of the PIV5 V gene facilitated the release and cell-to-cell spread of BoHV-5 in bovine cells.

First detection of adenovirus in the vampire bat (Desmodus rotundus) in Brazil.

This paper describes the first detection of adenovirus in a Brazilian Desmodus rotundus bat, the common vampire bat. As part of a continuous rabies surveillance program, three bat specimens were captured in Southern Brazil. Total DNA was extracted from pooled organs and submitted to a nested PCR designed to amplify a 280 bp long portion of the DNA polymerase gene of adenoviruses. One positive sample was subjected to nucleotide sequencing, confirming that this DNA fragment belongs to a member of the genus Mastadenovirus. This sequence is approximately 25 % divergent at the nucleotide level from equine adenovirus 1 and two other recently characterized bat adenoviruses.

Detection of Alphacoronavirus in velvety free-tailed bats (Molossus molossus) and Brazilian free-tailed bats (Tadarida brasiliensis) from urban area of Southern Brazil.

A survey was carried out in search for bat coronaviruses in an urban maternity roost of about 500 specimens of two species of insectivorous bats, Molossus molossus and Tadarida brasiliensis, in Southern Brazil. Twenty-nine out of 150 pooled fecal samples tested positive by reverse transcription-PCR contained fragments of the RNA-dependent RNA polymerase gene of coronavirus-related viruses. The sequences clustered along with bat alphacoronaviruses, forming a subcluster within this group. Our findings point to the need for risk assessment and continued surveillance of coronavirus infections of bats in Brazil.

Bovine herpesviruses do not play a major role in the differential diagnosis of rabies in cattle in southern Brazil

Background: Rabies has long been recognized as the major cause of encephalitis in cattle in Latin American countries. It has been estimated that nearly 50.000 cattle heads per year are lost due to encephalitis in that subcontinent, with a significant economic impact on cattle productive chains. In Brazil only, 2.500 to 3.000 cattle heads are estimated to be lost every year due to rabies. However, it is believed that rabies incidence in cattle is much larger, since usually only a few samples from affected animals in disease outbreaks are submitted to diagnostic laboratories. Rabies encephalitis is promptly and accurately diagnosed; however, particularly when rabies is excluded as causa mortis, the agent responsible for neurological disease of infectious origin often remains undetermined. Two bovine herpesviruses (BoHVs), bovine herpesvirus type 1 (BoHV-1) and bovine herpesvirus type 5 (BoHV-5) are major pathogens of cattle which are widely disseminated in Brazil. As usual in herpesvirus' biology, these tend to infect a large number of hosts and establish lifelong latent infections which may occasionally be reactivated. Both viruses, particularly BoHV-5, are often recovered from cases of neurological disease in cattle. The participation of BoHVs in the differential diagnosis of rabies must be evaluated. Besides, there might be associations between the occurrence of rabies and BoHV infections that deserve investigation. The aim of this study was to investigate whether bovine herpesvirus 1 and 5 would play a significant role in cases of neurological disease where rabies was the presumptive clinical diagnosis. In addition, associations between the occurrence of rabies and BoHV infections were searched for. The approach adopted for conducting such investigations was based on the search for viral nucleic acids as well as classical virus isolation on tissues of cattle submitted to rabies diagnosis over a two-year period, including rabies-positive and rabies-negative specimens. Materials, Methods & Results: Brain tissue samples of 101 cattle originally submitted to rabies diagnosis were collected over a two year period (2009-2010) from various municipalities within the state of Rio Grande do Sul, Brazil. Thirty nine of these samples had the diagnosis of rabies confirmed by standard laboratory diagnostic methods. Aliquots of tissues were submitted to DNA extraction and examined in search for genomes of bovine herpesviruses (BoHV) types 1 (BoHV-1) and 5 (BoHV-5) by as well as for infectious virus. Bovine herpesvirus genomes were detected in 78/101 (77.2%) samples, in which BoHV-1 genomes were detected in 26/78 (25.7%), BoHV-5 genomes in 22/78 (21.8%) and mixed BoHV infections (BoHV-1 and BoHV-5 genomes) were detected in 30/101 (29.7%) samples. In the 39 samples with confirmed rabies diagnosis, BoHV-1 DNA was detected in 9/39 (23%), BoHV-5 DNA in 6/39 (15.4%) and mixed infections with both BoHV types in 16/39 (41%) samples. However, no infectious herpesvirus was recovered from any of the specimens examined. Discussion: The high prevalence of BoHV1 and BoHV-5 infections was evidenced in the sampled population, but the absence of infectious BoHVs indicate that these were not associated to the occurrence of the cases of encephalitis where rabies was the primary suspicion. In addition, no association was detected between occurrence of rabies and detection of BoHVs, since the frequency of detection of herpesvirus genomes did not significantly differ between rabies-positive and rabies-negative samples. The detection of BoHV DNA in scattered areas of the brain with no infectious virus suggests that latency may take place in different regions of the brain.